Ackman's Pershing Square Capital Management has boosted its stake in Burger King Worldwide, which it helped bring back to the New York Stock Exchange just last week. Pershing Square now owns 12% of the fast-food chain.

Burger King returned to the public markets through a merger with Ackman's blank-check company, Justice Holdings. Pershing Square paid $1.4 million to finance the deal with private equity firm 3G Capital, which took BK private two years ago and which still owns some 70% of the company.